I don’t know the specific cause to it not connecting to the web app but as long as you have access to the physical server wherever you moved to, open your browser and attempt accessing your Plex Server by the following rather the Plex.tv method. If you truly do need to reclaim the server, you’ll be prompted with a opportunity to do so. This is something you can’t do over on the Plex.tv website only on the machine or device used to have Plex Server run on.
Accessing Plex Web App Directly in the Browser
On all platforms, you can access Plex Web App on your local network. From any computer on the local network:
http://[Local Plex Media Server IP Address]:32400/web
(e.g. http://192.168.1.25:32400/web) Or locally, from the computer running the server:
http://localhost:32400/web
or
http://127.0.0.1:32400/web
